Regulation of contraction of microfilament rings and control of extracellular matrix synthesis, polymerization, and degradation will be studied during embryonic development of a mollusk. Polar lobes are cytoplasmic protuberances which form and resorb on the fertilized eggs of the marine mudsnail, Ilyanassa obsoleta (Nassarius obsoletus), by constriction and relaxation of a microfilament ring. As in cytokinesis, ring constriction appears to be regulated by microtubules and calcium ions. We will isolate antibodies to highly purified proteins from muscle and non-muscle cells, label such antibodies, and use them to localize at the ultrastructural level the structural and regulatory proteins of the microfilament ring of the polar lobe constriction. We will use atomic absorption spectroscopy, isotopes, and ion-selective miroelectrodes to determine the intracellular ionic conditions controlling the activity of microfilament rings. Potential regulatory molcules or antibodies to them will be labeled and injected directly into eggs by microiontophoresis or pressure in order to alter microfilament function. Binding sites of injected substances, as well as normal endogenous sites of calcium sequestration, will be determined by electron microscopy. Normal and polar lobeless embryos will be compared for their ability to synthesize and secrete glycosaminoglycans and structural proteins. Egg capsules of Ilyanassa are transparent extracellular matrices composed of layers of banded ribbons and orthogonal gridworks of distinct tubules. Capsule area through which young snails hatch consists only of tubules. We will study how the tubules polymerize in orthogonal patterns, as well as isolate ribbon and tubules separately to allow identification and quantitation of their component amino acids and sugars. We will attempt to reassemble banded ribbons and tubules from extracted subunits. Hatching snails from normal and polar lobeless embryos will be examined for their ability to secrete hatching enzyme.